1. Field of the Invention
The present invention relates to a thermoplastic resin composition, particularly a thermoplastic resin composition reinforced by fiber material and containing an imide-modified copolymer. More particularly, it relates to a thermoplastic resin composition obtained by reinforcing a thermoplastic resin comprising, as an essential component, a mixture of a rubber-modified aromatic vinyl copolymer and an imide-modified copolymer obtained by reacting ammonia and/or a primary amine to a copolymer obtained by polymerizing a monomer mixture comprising an aromatic vinyl monomer and an unsaturated dicarboxylic acid anhydride, if necessary, in the presence of a rubber-like polymer, with fiber material selected from the group consisting of glass fiber, carbon fiber and aramide fiber.
2. Description of the Prior Art
Heretofore, there has been known a composition comprising glass fiber and a copolymer composed essentially of an aromatic vinyl monomer, an unsaturated dicarboxylic acid anhydride and other vinyl monomers (Japanese Unexamined patent publication No. 88189/1973). Such a composition comprising glass fiber and a copolymer obtained by the copolymerization of an unsaturated dicarboxylic acid anhydride, contains acid anhydride groups in the copolymer chain, which derived from the unsaturated dicarboxylic acid anhydride. Thus, such a composition is likely to undergo chemical changes and decomposition not only when contacted to water at a high temperature but also when subjected to heat. Therefore, its injection or extrusion molding is very much restricted, and when a product made thereof is contacted with water or steam, or exposed to a high temperature, the mechanical properties, particularly the impact strength, are likely to deteriorate.
U.S. Pat. No. 3,632,791 discloses a composition comprising glass fiber and a copolymer composed of from 40 to 95% by weight of an aromatic vinyl monomer, from 5 to 25% by weight of a maleimide and from 0 to 35% by weight of other monomers. However, in such a composition, the maleimide content is low, and the affinity of the copolymer to the glass fiber surface is inadequate. Further, the impact strength is inadequate since there is no substance serving to increase the impact strength such as a rubber-modified copolymer.